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Diffstat (limited to 'kernel')
-rw-r--r--kernel/cgroup.c20
1 files changed, 18 insertions, 2 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index e22df5d81e59..d57318950076 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2516,6 +2516,14 @@ static void cgroup_migrate_add_src(struct css_set *src_cset,
lockdep_assert_held(&cgroup_mutex);
lockdep_assert_held(&css_set_lock);
+ /*
+ * If ->dead, @src_set is associated with one or more dead cgroups
+ * and doesn't contain any migratable tasks. Ignore it early so
+ * that the rest of migration path doesn't get confused by it.
+ */
+ if (src_cset->dead)
+ return;
+
src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root);
if (!list_empty(&src_cset->mg_preload_node))
@@ -5258,6 +5266,7 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
__releases(&cgroup_mutex) __acquires(&cgroup_mutex)
{
struct cgroup_subsys_state *css;
+ struct cgrp_cset_link *link;
int ssid;
lockdep_assert_held(&cgroup_mutex);
@@ -5278,11 +5287,18 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
return -EBUSY;
/*
- * Mark @cgrp dead. This prevents further task migration and child
- * creation by disabling cgroup_lock_live_group().
+ * Mark @cgrp and the associated csets dead. The former prevents
+ * further task migration and child creation by disabling
+ * cgroup_lock_live_group(). The latter makes the csets ignored by
+ * the migration path.
*/
cgrp->self.flags &= ~CSS_ONLINE;
+ spin_lock_bh(&css_set_lock);
+ list_for_each_entry(link, &cgrp->cset_links, cset_link)
+ link->cset->dead = true;
+ spin_unlock_bh(&css_set_lock);
+
/* initiate massacre of all css's */
for_each_css(css, ssid, cgrp)
kill_css(css);